Microsurgery system for displaying in real time magnified digital image sequences of an operated area

ABSTRACT

A system captures and displays video of surgeries. The system may include at least one digital image sensor optically coupled to one or more lenses and configured to capture a video sequence of a scene in a surgery; at least one interface configured to receive at least one region on interest (ROI) of the captured video sequence; an electronic display, selected so that at least one of the digital image sensors has a pixel resolution which is substantially greater than the pixel resolution of the electronic display; and a computer processor configured to: receive the at least one captured video sequence and the at least one received ROI and display over the at least one electronic display a portion of the captured video sequence based on the at least one selected ROI.

This application is a Continuation-in-Part of PCT/IL2013/050764, filed10 Sep. 2013, which claims benefit of Serial No. 221863, filed 10 Sep.2012 in Israel and which applications are incorporated herein byreference. To the extent appropriate, a claim of priority is made toeach of the above disclosed applications.

FIELD OF THE DISCLOSED TECHNIQUE

The disclosed technique relates to microsurgery, in general, and tosystems and methods for displaying in real-time magnified digital imagesequences of an operated area for allowing a user to perform proceduresin the operating room, or microsurgery in particular.

BACKGROUND OF THE DISCLOSED TECHNIQUE

Microsurgery is a general term for surgical procedures utilizing asurgical microscope to perform intricate operations on small structures.Through the microscope the surgeons sees magnified imaged of thestructures or tissues. Currently microsurgery procedures utilize aclassic conventional optical microscope. The basic conventional surgicalmicroscope is constructed of high quality optical components, zoomobjective lens, eyepiece for user view, light source and an XY motor.Microscopes usually have provision to have additional eyepieces forassistance. For some procedures, like neurosurgery, the microscope isconnected to complex motion structures, providing motion in even 6degree's in space. In addition, there are some more add-ons for specialfunctions like cameras to capture/record the operation, projectiondisplays to project symbols, UV light sources etc. The common ground forsurgical microscopes is the stereo image, their fixed position above thepatient (around 20-40 cm) and the connection of the user (or surgeon) tothe microscope which sees the relevant object through direct opticalchannels. There are techniques to fold the light rays in the microscopeto design a more comfortable and ergonomic structure for the user.However, because the microscopes are based on direct light rayschannels, they are limited in their ability and flexibility to locateand shift the eyepiece. Simply put, the eyepiece of the conventionalsurgical microscope is mechanically connected to the optical system ofthe microscope, making the surgeon connected the microscope as well.During prolonged use of the microscope (in particular, surgicaloperations), the user must position her head fixed to the microscope fora long period of time. The long time that the user holds her head fixedto the microscope causes neck/back pains, fatigue and may influence theprocedure quality.

Conventional microscopes are bulky and big, located in the mostsensitive areas in the operation room, above the patient. Themicroscopes may obstruct the view and the motion of the medical staffaround the operated area. When more than a single surgeon uses theconventional surgical microscope, all surgeons are constrained to viewthe same image with the same magnification. If the additional surgeonwould have wishes to view a different field or a portion of the samefield but at a different magnification, an additional microscope wouldhave been required, thus further encumbering the operating room. Furtheradditionally, due to the classic direct view method of the microscope,with no digital means and sensors, the users do not benefit the digitaldomain advantages.

Reference is now made to US Patent Application Publication No.2009/0245600, to Hoffman et al., and entitled “Automated Panning andDigital Zooming for Robotic Surgical Systems”. This publicationdescribes an endoscopic system for minimally invasive procedures. Theendoscopic system acquires endoscopic images at a slightly higherresolution than that of the display, thereby allowing for digital zoomor panning. That is, the system selects a region of interest (ROI) fordisplaying to the user and crops the ROI out of the acquired image tofit into the display. The user views the cropped ROI via dedicatedeyepieces or monitor, and therefore cannot move freely around theoperating room while viewing the ROI. This publication describesemploying robotic arms for performing surgical operations. The roboticarms obstruct the operating area. For example, the robotic arms mightocclude a portion of the operating area and might obstruct the surgeon'saccess to the operating area. The camera in this publication is anendoscopic camera fitted into an endoscope and is therefore limited insize and resolution.

Reference is now made to International Patent Application PublicationNo. WO2011/142165, to Ogawa, and entitled “Operation Input Device andManipulator System”. This publication describes an operation inputdevice for employing robotic arms for performing remote surgeries. Theoperation input device includes a display, an operation unit, ahead-mounted unit, relative position sensors, and a control unit. Theoperation unit operates a displayed object (e.g., a surgical roboticarm), which is displayed upon the display. The relative position sensorsdetect the relative position and the relative orientation of thehead-mounted unit with respect to the operation unit. The control unitactuates the displayed object which is displayed within the display onthe basis of the relative position and the relative orientation thathave been detected by the relative position sensors.

SUMMARY OF THE DISCLOSED TECHNIQUE

It is an object of the disclosed technique to provide a novel method andsystem for displaying in real time magnified digital image sequences ofan operated area, which overcomes the disadvantages of the prior art. Inaccordance with the disclosed technique there is thus provided amicrosurgery system including a Head Mounted Display (HMD), at least onecamera, a memory unit and a processing device. The processing device iscoupled with the HMD, the camera and with the memory unit. The camera issuspended above an operated area, and acquires operated area imagesequences of the operated area. The memory unit stores the operated areaimage sequences. The processing device receives an input indicating aRegion of Interest (ROI) of the operated area. The size of the operatedarea is larger than the size of the ROI. The processing device producesmagnified image sequences of the ROI from the operated area imagesequences. The HMD displays to a user in real time the magnified imagesequences of the ROI. The camera is mechanically and opticallydisconnected from the HMD.

In accordance with another embodiment of the disclosed technique, thereis thus provided a method for displaying in real time magnified digitalimage sequences of an operated area. The method includes the steps ofacquiring operated area image sequences, receiving an input indicating aRegion of Interest (ROI); producing magnified image sequences of the ROIand displaying in real time the magnified image sequences of the ROI.The operated area image sequences are acquired from a viewpointsuspended above the operated area. The size of the operated area islarger than a size of the ROI. The magnified image sequences of the ROIare produced from the operated area image sequences. The magnified imagesequences of the ROI are displayed to a Line of Sight (LOS) of a user,which is independent of the viewpoint of the operated area imagesequences.

BRIEF DESCRIPTION OF THE DRAWINGS

For better understanding of embodiments of the invention and to show howthe same may be carried into effect, reference will now be made, purelyby way of example, to the accompanying drawings in which like numeralsdesignate corresponding elements or sections throughout. In theaccompanying drawings:

FIG. 1 is a schematic illustration of a microsurgery system fordisplaying in real-time ROI image sequences of an ROI of an operatedarea, constructed and operative in accordance with an embodiment of thedisclosed technique;

FIG. 2 is a schematic illustration of a block diagram of a microsurgerysystem for displaying in real-time ROI image sequences of an ROI of anoperated area, constructed and operative in accordance with anotherembodiment of the disclosed technique;

FIGS. 3A and 3B are schematic illustrations of a stereoscopic opticalsystem for acquiring a stereoscopic image pair by employing a singlesensor, constructed and operative in accordance with a furtherembodiment of the disclosed technique;

FIG. 4 is a schematic illustration of a mounted microsurgery systemmounted on a robotic arm, constructed and operative in accordance withyet another embodiment of the disclosed technique;

FIGS. 5A, 5B and 5C, are schematic illustrations of a focus-controlsystem, constructed and operative in accordance with yet a furtherembodiment of the disclosed technique;

FIG. 6 is a schematic illustration of a tissue-penetration system forimaging subcutaneous tissues, constructed and operative in accordancewith yet another embodiment of the disclosed technique;

FIG. 7 is a schematic illustration of a microsurgery system, whichparallax can be adjusted, constructed and operative and accordance withyet a further embodiment of the disclosed technique;

FIGS. 8A-8E are schematic illustrations of a lighting system including ashutter module, constructed and operative in accordance with yet anotherembodiment of the disclosed technique;

FIGS. 9A, 9B and 9C, are schematic illustrations of an HMD fordisplaying a high resolution image to the fovea and displaying a lowerresolution image to the periphery of the eye of the user, constructedand operative in accordance with yet another embodiment of the disclosedtechnique;

FIGS. 10A and 10B are schematic illustrations of a display system havingadjustable eyepieces, constructed and operative in accordance with yet afurther embodiment of the disclosed technique; and

FIGS. 11A, 11B, 11C and 11D, are schematic illustrations of a virtualdepth of field scheme for presenting to a user a selected virtual depthof field, operative in accordance with yet another embodiment of thedisclosed technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

1 Basic System

Before expansion of the drawing details, the following paragraphsbriefly describe some aspects and building blocks of the systems of thedisclosed technique. The disclosed technique relates to a microsurgerysystems designed to replace a conventional surgical microscope in theoperating room (OR). The microsurgery system of the disclosed techniqueincludes digital cameras suspended above the operated area, Head MountedDisplay (HMD) and a processor. Additionally a light source and monitorare usually integrated with the system. The cameras can be mounted on asupport arm (e.g., attached to the ceiling, the wall or supported on apole). The cameras and HMD are used to display to a user, in real-time,live video (image sequences) of an operated area, allowing the user toperform microsurgical procedures. While using the disclosed technique,the user performs microsurgery procedure without employing aconventional surgical microscope, which can be removed from the ORaltogether.

The processor captures the data from the cameras, processes it andtransmits it to the HMD's and monitors. Each user can control the dataand processing functions made for his display or use. The cameras andthe HMD are not mechanically connected (i.e., are mechanicallydisconnected), and are optically disconnected. Thereby, the user's headposition is not limited or constrained, by the position of the surgicalmicroscope (like conventional microscopes constraining the position ofthe eyepieces). Additionally the cameras are suspended above theoperated area, and therefore do not obstruct the operated area (i.e., donot occlude the operated area and do not physical obstruct the user'saccess to the operated area). That is, removing the surgical microscopefrom the OR and replacing it with cameras suspended above the operatedarea frees the OR from the physical obstruction caused by theconventional surgical microscope. Thereby, the user is provided withmore freedom to move around the OR, and in particular around theoperated area (i.e., also referred to as the target area).

In accordance with one embodiment of the disclosed technique, the systemincludes at least two high resolution video cameras suspended above theoperated area, a processing device and an HMD. The cameras capture imagesequences of the operated area (i.e., operated-area image sequences)from at least two slightly different perspectives. The processing devicereceives the operated-area image sequences and produces therefromstereoscopic, or three dimensional (3D), image sequences of the operatedarea. The processing device presents the image sequences to the user viaan HMD in real-time. The user performs microsurgery procedures based onto the 3D image sequences.

The image resolution of the cameras is much higher than that of thedisplay components of the HMD, such that for small magnifications, theacquired operated-area image sequences must be downscaled or resized tofit into the display. For example, for displaying an area smaller thanthe full image frame, the processing device determines an ROI within theacquired operated-area image sequences. The processing device crops ROIimage sequences from the acquired operated-area sequences, resizes it tofit the display resolution, and displays the ROI to the user via theHMD. The term ROI image sequences, as referred to herein below, refersto the cropped ROI portion cropped from the acquired operated-area imagesequences. The term ROI image sequences may further relate to (i.e., theROI image sequences may further include) metadata relating to theviewing angle, type of objects to be viewed, and further data that maybe presented within the ROI image sequences such as messages and alerts.

HMD 208 is a dual-eye display. Employing HMD 208 detaches the user froma monitor or eyepieces and enables her to move freely around the OR.Additionally, the ROI can be slaved to HMD 208 (i.e., as tracked bytracker 218) thereby conveniently providing the user with the ROI imagesequences she is interested in. HMD 208 can allow 2D or 3D view,according to the nature of the application and video source. HMD 208 mayinclude display optics in front of one, or of each eye.

Angular resolution is the angle of the smallest apparent objectnoticeable in the electro optical system. The angular resolution of animage forming device, describes its ability to distinguish small detailsof a scene at a selected distance. In a camera, the angular resolutionwill be referred as Instantaneous Field of View (IFOV), and is given bythe pixel size divided by the effective focal length of the optics(e.g., measured in radians). Thus, the IFOV of the camera is a propertyof the pixel and of the optical system, and is not related to the numberof pixels in the image sensor. For a given IFOV, the number of pixels ofthe camera sensor (i.e., the pixel count) defines the Field of View(FOV); or together with the distance to the object, defines the size ofthe captured area. The cameras of the microsurgery system of thedisclosed technique have IFOV that is small enough to resolve details ofmicrometric dimensions (e.g., five microns) in the operated area, fromthe position of the cameras suspended above the operated area. It isnoted that in a monitor display, the IFOV is the smallest projectionelement divided by the distance to the viewer. In an HMD the IFOV is thesmallest projection element divided by HMD focal length.

The HMD of the microsurgery system of the disclosed technique has anIFOV close to the human eye limit, achieved by the ratio between thepixel size and the effective focal length. That is, the HMD allows theuser to view the displayed image sequences at the highest acuity (i.e.,lowest IFOV) the user eye is capable of. The IFOV of the HMD, togetherwith the display resolution of the HMD, provide the required HMD FOV atthe desired acuity to allow the user to perform a microsurgicalprocedure.

The magnification of a system with a camera and a display isproportional to their ratio. The IFOV of the cameras and distance fromobject sets the smallest visible object that can be digitally captured.The pixel count of the cameras sets the area covered by the camera. Theratio between the display IFOV and the camera IFOV sets the maximummagnification in such a manner (e.g., for observer located 40centimeters (cm) from the object):

${{Maximum}\mspace{14mu}{Magnification}} \approx \frac{40\mspace{14mu}{{cm} \cdot {IFOV}_{HMD}}}{{Camera}\mspace{14mu}{{Distance} \cdot {IFOV}_{camera}}}$

To achieve a large range of magnifications, the camera pixel count mustbe larger than of the pixel count of the display. Pixel count describesthe number of pixels of a camera sensor or of a display. For example, ifthe HMD has IFOV close to the human high, around 0.0003 radians and thecamera IFOV is 0.00001 radians the maximum magnification, for a cameradistance of 40 cm is 30. If the HMD resolution is 1920×1200, than tocreate a range of magnifications between 10 and 30, the cameraresolution should be at least 5760×3600 pixels. That is to cover thefull HMD display area with the entire range of magnifications.

The microsurgery system of the disclosed technique can provide digitalobject magnification at least comparable with that of conventionalsurgical microscopes. Digital image magnification eliminates the need(or at least compliments) for optical zoom mechanism. Thus, themicrosurgery system of the disclosed technique can operate without anoptical zoom mechanism, thereby saving the space and the costs thereof.Additionally, changing the optical zoom requires mechanical movement oflenses which might take more time than digital magnification via imageprocessing, and is more prone to wear and tear. Further additionally,the digital images and digital image magnification allows for furtheradvantages associated with the digital domain, such as fast movementsbetween ROIs. That is, the system can switch an image of a first ROIwith an image of a second ROI between frames.

The microsurgery system of the disclosed technique images a largeoperated area at all-times, and thereby can improve the situationalawareness of the user and can be used for additional applications. Thatis, in a conventional surgical microscope of the prior art, the observed(i.e., and magnified) FOV is narrow and gets even narrower withmagnification. The user of the conventional surgical microscope mightmiss important visual cues outside the observed field. The microsurgerysystem of the disclosed technique captures visual data from a largearea, even if the user is currently interested (i.e., magnifies andobserves) a narrower ROI. Thereby, the microsurgery system can providedata respective of the area surrounding the ROI, which may be pertinentto the surgery or can be used for situation awareness, fast jump betweenareas, image processing and tracking, etc.

The microsurgery system displays the full operated-area image sequences,or the magnified ROI image sequences, in real-time such that the usercan perform a microsurgical procedure in real-time, accordingly.Therefore, the time lag from the acquirement of the operated-area imagesequences to the display of those images, or of the ROI image sequencesshould be very brief. Delays can impact performance of operation and cancreate discomfort, fatigue, and the like, to the user. The term“real-time” as referred to herein below relates to an instantaneousaction, or a very short time lag, allowing for smooth operation of theuser. That is, the user should not experience noticeable time lagbetween an event occurring on the object plane and the display of thatevent. Short latency can be achieved using fast read out cameras,powerful processors and efficient logic and algorithms implemented inthe processors. In some embodiments the latency can be decreased bygrabbing and processing only the regions of interest and, therebydecreasing the required data band width.

Reference is now made to FIG. 1, which is a schematic illustration of amicrosurgery system, generally referenced 100, for displaying inreal-time image sequences of an operated area, constructed and operativein accordance with an embodiment of the disclosed technique. Withreference to FIG. 1, microsurgery system 100 includes a pair of cameras102 and 104, a processing device 106 and a Three Dimensional (3D) HMD108. Processing device 106 is coupled with each of cameras 102 and 104,and with HMD 108. Microsurgery system 100 is installed within an OR (notreferenced) and replaces a conventional surgical microscope. That is,microsurgery system 100 allows the user to perform microsurgeries bypresenting to the user image sequences of the operated area (notreferenced) in real-time, and at a desired magnification.

As can be seen in FIG. 1, cameras 102 and 104 are suspended above theoperated area. Cameras 102 and 104 do not obstruct the user fromaccessing the operated area. Cameras 102 and 104 are mechanically (andoptically) disconnected from HMD 108. The captured image sequences aredisplayed via HMD 108. Thus, the user is not constrained to an eyepieceor a monitor and is free to move around the operating room.

In a nutshell, microsurgery system 100 operates in the following manner.Cameras 102 and 104 capture image sequences of the operated area (i.e.,also referred to as operated-area sequences). Processing device 106determines a Region of Interest (ROI) of the operated area. For thegeneral purpose from here on, ROI can also be considered as the fulloperated-area frame. Processing device 106 produces ROI image sequencesfrom the acquired operated-area sequences and presents the ROI sequencesto the user via HMD 108. The pixel count of cameras 102 and 104 ishigher than that of HMD 108, and therefore the operated-area sequencesshould be resized (i.e., downsized) for fitting into the display.Additionally, in case the ROI is only a portion of the operated area,processing device 106 crops the respective portion from theoperated-area sequences for producing the ROI sequences. For example,assuming the user wishes to view a selected section of the operatedarea, processing device 106 would crop the portions of the operated-areasequences showing that selected section, and would downsize the croppedportions for producing the ROI sequences. The ROI size and the resizingvalue, along with the camera distance from the object, will determinethe magnification.

Processing device 106 can further perform additional image processingoperations on the captured sequences. Moreover, processing device 106can further present to the user additional data (e.g., medical history;physiological measures; and medical imaging data, such as CT or MRI)overlaid on the captured sequences. As mentioned above, the displayedROI sequences can further include metadata relating to magnification,illumination levels, data on of objects to be viewed, symbolics,guidance and data that may be presented within the ROI sequences such asmessages and alerts.

Reference is now made to FIG. 2, which is a schematic illustration of ablock diagram of a microsurgery system, generally referenced 200, fordisplaying in real-time ROI image sequences of an ROI of an operatedarea, constructed and operative in accordance with another embodiment ofthe disclosed technique. Microsurgery system 200 includes a pair ofcameras 202 and 204, a processing device 206, a 3D HMD 208 having atracker 218 (e.g., a head tracker or/and an eye tracker), a medicalimaging image source 210, a medical file data source 212, aphysiological measures source 214, a light source 216, a monitor 220, acommunication interface 222 and a remote data site 224. Microsurgerysystem 200 can further include user interfaces, such as joysticks,keyboards, levers, buttons, pedals to be used by the user using herfeet, and the like. Processing device 206 is coupled with each of thepair of cameras 202 and 204, 3D HMD 208, tracker 218, medical imagingimage source 210, medical file data source 212, physiological measuressource 214, light source 216, monitor 220, and with a remote data site224 (i.e., via communication interface 222). Processing device 206includes, or is coupled with, a memory unit (not shown) for storing datathereon.

The following paragraphs provide a general description of the operationof microsurgery system 200. Thereafter, each of the components of themicrosurgery system would be described more elaborately, followed bysome additional functionalities and embodiments of the system. Duringoperation, cameras 202 and 204 capture video sequences of the operatedarea (i.e., operated-area sequences). Processing device 206 receivesinput indicating an ROI (e.g., indicating the location and size of theROI) in the operated area, and accordingly produces respective ROIsequences from the acquired operated-area sequences (i.e., by resizingand possibly cropping). That is, processing device 206 crops a portionof the captured operated-area sequences according to the determined ROI(i.e., crops the respective portion of the acquired sequences showingthe ROI), and resizes the cropped sequences for producing ROI imagesequences. Processing device 206 displays the ROI sequences to thesurgeon via HMD 208.

For example, processing device receives input detailing the Line of Site(LOS) of the head or of the eye of the user from tracker 218. Processingdevice 206 determines the ROI according to the tracked LOS. The ROI canbe also extracted from user input received via a joystick, a keyboard, afoot pedestal, voice activation, and any other input device. Accordingto another embodiment of the disclosed technique, the ROI is derived bytracking a point of a tool (e.g., a scalpel) held by the surgeon orother features in the image. In this case the ROI can be updated inreal-time as the operation progresses.

Microsurgery system 200 allows zooming in to the image digitally,providing digital XY translation motion of the image, and simultaneouslyproviding different users with different ROI image sequences. Bycapturing the full camera resolution at all-times, microsurgery system200 can perform the following, exemplary, functions:

-   -   Record the entire FOV of the cameras for debriefing and later        analysis.    -   Share the image observed by the user for the purpose of teaching        or receiving assistance.    -   Serve multiple users, including staff or processors.    -   Keep track of features not currently observed by the surgeon and        out of his current field of view.    -   Save bookmarking of areas or other ROI's in the image.

The following paragraphs elaborately describe the various components ofmicrosurgery system 200. As mentioned above, cameras 202 and 204 replacethe conventional surgical microscope, which can therefore be removedfrom the operating room completely. By replacing the conventionalsurgical microscope, and enabling removal thereof from the operatingroom, the microsurgery system of the disclosed technique removes anobstruction from the operated area. Thereby, a better view and morespace are available to the medical staff around the operated area. Eachof cameras 202 and 204 can includes optical elements, such as lenses(e.g., objective lenses or field lenses), prisms, and every otheroptical component required for acquiring high resolution, large FOVimages.

Cameras 202 and 204 can either be fixed in place or moveable by adedicated mechanism. Cameras 202 and 204 are suspended above theoperated area. Cameras 202 and 204 can be suspended from the ceiling, awall or from a support frame (e.g., a support frame mounted on the flooror a suspended support arm). In this manner, cameras 202 and 204 do notobstruct the operated area (i.e., do not occlude the operated area toany of the users, and do not physically obstruct access to the operatedarea). In accordance with another embodiment of the disclosed technique,cameras 202 and 204 have objective lenses capable of focusing on objectsat a distance of tens of Centimeters, for example, 15-150 Centimeters.Thereby, cameras 202 and 204 can be suspended above the operated area,and capture the image sequences of the operated area from a far.

Cameras 202 and 204 capture operated-area image sequences from twodifferent perspectives to be displayed to each eye, providing 3Dimaging. It is noted that the relative position of the cameras, fromeach other, can also be varied, for example, according to the distancefrom the object. Alternatively, more cameras can be employed forcapturing operated-area sequences from various perspectives. Forexample, microsurgery system 200 can include three, four, or sixcameras. In this manner, the 3D captured data is enriched, andocclusions to a selected camera can be compensated for. Furtheralternatively, a single camera is employed for capturing images fromdifferent angles by utilizing a special optical assembly or an actuatingassembly.

Processing device 206 controls cameras 202 and 204, and can controlAutomatic Gain Control (AGC), Exposure Control (EC), Iris Control andany other control method for setting the cameras working point. Inaddition processing device 206 can set the frame rate of cameras 202 and204.

Light source 216 is arranged to illuminate the operated area. Forexample, light source 216 can be arranged to illuminate the operatedarea from the cameras optical LOS creating a coaxial or semi coaxialillumination. In some applications the light source can producecollimated illumination. Another approach is to illuminate from asingular point at some location near the lens creating a flood light. Athird approach may be to use more than a single light source. Forinstance, the multiple sources can be the ones described in the firsttwo approaches. Alternatively, a ring of light sources can be designedaround the lens. The distribution of light sources can be arranged toproduce uniform light with less shadowing in the image.

Additionally, one or more of light sources 216 can illuminate in theNear-Infrared (NIR) spectrum, UV or any other light spectrums forcapturing video sequences at the respective spectrums, or for exciting afluorescent agent. The different illumination spectrums can be producedby different light sources, or by employing different filters. Insteadof designing the light sources for different spectrums, or in addition,the camera can be designed to capture images in different spectralbands.

Processing device 206 can be replaced by another processing device or anarray of processing devices, and can have either a centralized or adecentralized configuration. The memory unit can be replaced by, oraugmented with, other data storage devices.

Monitor 220 can display the acquired image sequences, or cropped andresized portions thereof. Thereby, all personal within the OR (and notonly those equipped with an HMD) can view the acquired sequences.Alternatively, processing device 206 employs monitor 220 for displayingadditional data, such as the medical history of the patient.

Medical imaging image source 210, medical file data source 212, andphysiological measures source 214 are all data sources for providingexternal data, which can be displayed to the user besides the ROI imagesequences. These data sources would be detailed further herein belowwith reference to section 6.

Tracker 218 can be a head tracker, an eye tracker, or both, for trackingthe position and orientation, or at least the Line of Sight (LOS) of theuser. Tracker 218 can be an optical tracker, a magnetic tracker, anultrasonic tracker, or any other tracker, and would be detailed furtherherein below with reference to section 4.

Communication interface 222 enables microsurgery system 200 tocommunicate with a remote data site 224, for example for providing imagesequences of the operated area to remote data site 224, or to receivedata from remote data site 224. For instance, microsurgery system canprovide ROI image sequences to a surgeon located on a remote site, incase the user wishes to consult with that surgeon. Communicationinterface 222 would be detailed further herein below with reference tosection 5.

It is noted that out of the components of microsurgery system 200detailed herein above, only the cameras, the processing device and theHMD are compulsory—everything else is optional and various combinationscan be constructed (or employed) for various tasks, procedures, andresource constraints.

2 System Features

Other functionalities and structures of microsurgery system 200 aredescribed herein. The optics (not shown) of cameras 202 and 204 canprovide further magnification (i.e., optical magnification). In thismanner, the cameras do not provide unmagnified images, and themagnification range of microsurgery system 200 begins at the opticalmagnification factor and extends by digital magnification. For example,if optical design of the cameras produces optical magnification of afactor of four (×4) and the digital magnification can be up to ×6, themagnification range would be ×4-×24. Put another way, the camerascapture images at a constant optical magnification, and can furtherprovide digital magnification due to their high resolution design.

As mentioned above, cameras 202 and 204 provide the capturedoperated-area sequences to processing device 206. Processing device 206crops and resizes the image sequences for producing ROI image sequencesand provides the ROI sequences to HMD 208 for displaying to the user.Microsurgery 200 captures a wide FOV images. The objective optics of thecameras produce (i.e., focus) an image of the operated area to becaptured by the cameras (i.e., by the sensors of the cameras). Inaccordance with one embodiment of the disclosed technique, the camerascapture wide FOV images covering the image of the operated area asfocused by the objective optics of the cameras. After determining theROI, processing device 206 produces ROI image sequences from thecaptured operated-area sequences by cropping a respective portion of thecaptured operated-area sequences (and resizing it).

In accordance with another embodiment of the disclosed technique, thecamera IFOV is the same as in the previous embodiment but the FOV of thecamera is smaller (smaller sensor resolution). In this case, the camerasare capable of mechanical motions, like XY movement or optical zoom, tocapture FOV extending beyond the camera FOV (i.e., to be able to captureevery location of the FOV of the objective optics). The camera capturesa portion of the FOV of the objective optics respective of thedetermined ROI, thereby decreasing the amount of data to be handled bythe system, while still maintaining the necessary IFOV. For instance,the LOS of the camera can be enslaved to a head tracker, or to an eyetracker (or to another user interface, such as joysticks), for capturingROI image sequences. It is noted that the captured ROI image sequencesmight still require resizing to fit the display, depending on the pixelcount of the camera and that of the display. The XY motion mechanism canbe implemented by a bi-axial steering mirror that scans the imageobtained by the objective optics through a wide FOV. The position and/ororientation of the mirror is enslaved to the user's head (or eye)movements (or controlled by another user interface), replacing thecropped area of the solution mentioned in the previous paragraphs.Another method for shifting the LOS of the camera is using pan and tiltmechanism of some elements of the system.

In accordance with yet another embodiment, there is a combination of thetwo previously described embodiments (i.e., the embodiments of the wideFOV camera sensor that captures the entire FOV of the objective opticsand of the narrower FOV camera sensor with the scanning mechanism). Inthe combined embodiment, the camera sensor has a moderate FOV and iscomplimented by scanning possibilities. In addition a selected ROI imagesequence is cropped and resized for displaying to the user.

As mentioned above, processing device 206 receives the operated-areaimage sequences acquired by cameras 202 and 204, and receives inputindicating an ROI of the operated area (e.g., the LOS of HMD 208determined by tracker 218 or from the joysticks movements). Processingdevice 206 crops and resizes the acquired image sequences for producingROI sequences. The cropping of the ROI sequences out of the full framecan be carried out in several methods. The first method involvesgrabbing the full image out of the sensors of cameras 202 and 204. Inthis method the ROI portion is digitally cropped from the full imageafter the grabbing. The second method involves grabbing only the ROIportion from the sensors of cameras 202 and 204 (and not the fullframe). The grabbing can be made by addressing only the relevant pixelsin the image array. In the first two methods, processing device 206performs image resize on the cropped ROI portion so it will fit theresolution of HMD 208. In case the ROI covers the entire captured field,so that no cropping is required, the digital image sensors of cameras202 and 204 can be configured to under-sample for adjusting the pixelcount of the video sequence to the pixel count of HMD 208. An example ofunder-sampling is the sampling of every second pixel in the arrayinstead of every pixel.

In accordance with another embodiment of the disclosed technique, lightsource 216 can provide visual guidance to the user. For example, if thelight is in the visible spectrum, it can be used to mark areas ofinterest, mark places to perform surgery cuts, direction symbol, and thelike. Illuminating in the near-infrared can be used for structured lightapplications. The structured light is used to produce 3D data base ofthe objects. The projector can be of any type, such as DigitalMicromirror Device (DMD), Pico Micro-electro-mechanical Systems (MEMS)projector, Liquid Crystal Display (LCD), Cathode Ray Tube (CRT), and thelike.

Cameras 202 and 204, and light source 216 can be digitally controlled.For example, system 200 can employ algorithms like AGC and AEC tocalculate and set the camera working point. The gain and exposure areusually calculated to produce image with maximum dynamic range andminimum saturations. With a single or multiple light sources anAutomatic Light Control (ALC) may be used. Based on the image thealgorithm calculates the light levels of the single or multiple lightsources. The controllable light sources facing the scenes aredynamically adjusted based on a dynamic analysis of the image histogramof the video sequences. The level of the lights are adjusted to optimizethe contrasts, dynamic range and to minimize specular reflections fromobjects.

Alternatively the light source can be time modulated. In this case thesource transmits pulses of light in some kind of time scheme (Meaning,the light source is turned on and off multiple times per second orminute) and the cameras are synchronized to the light source timeregime. This synchronization of the cameras and the light source can beused for some features of the microsurgery system, exemplary ones aredetailed in the following paragraphs. For example, if the integrationtime of the camera is lower than the cameras frame time (inverse of thecamera refresh rate) the light source on time can be reduced to overlapwith the camera integration time. Illumination power is saved in thiscase. Another example is time of flight technique or gated imaging. Thatis, the source is configured to transmit a very narrow pulse (with time)of light. The camera is synchronized to open its shutter only after thetime of which the pulse has traveled to the object and came back. Thistechnique can be used with one pulse per frame or with multiple framesper frame to increase the signal received by the camera. By known andcorrect synchronization of the camera and light source, using thismethod can help to create a 3D data base of the object or even topenetrate the tissues.

Alternatively the light source can be designed to illuminate theoperated area with different intensities. For instance, the operatedarea is divided into sub areas smaller than the operated area. Each areais illuminated with different intensity to increase to dynamic range ofthe image and illuminate saturations, dazzling, dark spots and so on. Inthe simplified manner each sub area can be illuminated using differentlight source. Each light source is controlled separately to derive itsindividual illumination value. A more efficient manner is a light sourcedesigned with array of switching shutters. The light source illuminatoris composed of a source (e.g., LED, Xenon, Laser, Halogen, Fiber, etc.)and an optical module designed to illuminate the operated area with thesource. The optical module is usually designed to transmit in arelatively narrow angle and to create a uniform illumination spot on theoperated area. The shutter array is implemented inside the opticalmodule in a location where the beam is collimated, semi collimated, inan aperture stop, field stop or in a focal plane. In this way eachshutter controls the illumination level correlated to a specificdirectional illumination of the operated area.

The shutter arrays can be transmitting shutters like LCD array, orreflective shutters like digital micro mirror device (DMD). For thepurpose of the following description we will use the DMD as the shutterarray. The light source illuminates in a relatively large angle andnon-uniform pattern. A set of first lenses can be used to collect thelight rays from the source to the shutter array. As an example, thefirst lenses focus the light beam to the shutter array. When the all themirrors of the array are in the ON position the set of second lensescollimates the image created on the shutter array to the operated area.The image created on the shutter area falls and multiple small shutters(in the case of DMD, can reach millions of micro mirrors). Reflectionfrom each mirror on the area corresponds to a small area on the operatedarea. For a specific mirror, if it is OFF position, the small areacorresponding to that specific mirror will not be illuminated. If theshutter area is operating in higher rate than the frame rate of thecamera, then the small area can be partly illuminated by controllingeach micro mirror frequency per camera frame.

The processor controls the value of each of the shutter in the shutterarray. They can be configured in advance or can be dynamically changedaccording to the image for example. If the processor identifies that anarea in the image is saturated it can decrease the illumination levelfrom the corresponding shutters. Separately, or together with the cameragain and exposure control, this can increase significantly the dynamicrange of the image.

Alternatively, the camera sensor can be gated. In this manner, each ofthe camera pixels can be configured individually for its triggering. Theconfiguration can incorporate the number of ON and OFF exposure openingper frame (multiple pulses per frame) and can incorporate the timeduration of the on time and off time (pulse widths). By controlling theexposure time of each pixel the dynamic range of the image can beincreased.

2.1 Voice Activation

Microsurgery System 200 can further include a voice control moduleallowing control of system 200 via voice activation. Voice activationallows hands-free control, leaving the user's hands free to perform anytask, while providing a flexible and a rich control interface. The voicecontrol module allows the identification of pre-programmed keywords,reserved for specific purposes, to be used by any user, and to allowusers to program their own keywords, independent of a language ordictionary. For example, the oral command “markers on” may addpre-defined markers onto the displayed image. The voice control modulecan be programmed to include any command required for a specific user.

The voice control can be programmed to be adapted to users speakingdifferent languages. For example, a Spanish-speaking user may supplementthe English commands with its native language commands by programmingthe Spanish commands herself.

Voice activation can be used in conjunction with the head and eyetrackers to construct elaborate yet intuitive user interface. Forexample, a “zoom on” oral command may toggle on ahead-movement-dependent zoom function. For instance, moving the headforward zooms into the image, while moving it backwards zooms out. A“zoom off” command toggles this feature off, allowing for normaloperation.

2.2 Gestured Control

In accordance with another embodiment of the disclosed technique,microsurgery system 200 can further include a gesture control moduleallowing control of system 200 via gestures. That is, the head trackeror eye tracker of the microsurgery system captures the head or eyemovements of the user. The processing device interprets predefinedgestures, and accordingly operates respective functions of themicrosurgery system. For example, the user can move her head forward toactivate a “zoom in” function, or move her head away to activate a “zoomout” function (the same can be for focus instead of zoom). Anotherexample can be shifting between screens displayed on the HMD. Fast headmovement (or other defined movement pattern) to theleft/right/top/bottom (or any other direction) toggles between differentscreens or image source inputs (or in the general manner differentconfigurations). The gesture control module can be activates anddeactivates by a predefined gesture (or a voice command or a button), toavoid movements from being interpreted as unintentional gestures.

More specifically, the head movements can be used in a virtual menu seenon the HMD. The user activates the virtual menu by a predefined gesture(or a voice command or a button). Once the virtual menu is operated theuser can activate the functions of the virtual menu be moving the heador eyes to that specific button or function.

2.3 Stereo Imaging

Reference is now made to FIGS. 3A and 3B, which are schematicillustrations of a stereoscopic optical system, generally referenced300, for acquiring a stereoscopic image pair by employing a singlesensor, constructed and operative in accordance with a furtherembodiment of the disclosed technique. FIG. 3A depicts a stereoscopicsystem including two optical systems and a single image sensor. FIG. 3Bdepicts a stereoscopic system further including an infrared sensorcomplimenting each of the optical systems. Stereoscopic optical system300 can be incorporated into the microsurgery system of the disclosedtechnique for acquiring stereoscopic images of the operated area with asingle ultrahigh resolution sensor, replacing both cameras (e.g.,replacing cameras 102 and 104 of FIG. 1, or cameras 202 and 204 of FIG.2).

In FIGS. 3A and 3B only one side of stereoscopic system 300 isenumerated, though the description applies to both sides. With referenceto FIG. 3A, stereoscopic system 300 includes an optical relay system302, a dynamic mirror 304, a fixed mirror 306, and an image sensor 308.Optical relay system 302 is optically coupled with dynamic mirror 304,which in turn is optically coupled with fixed mirror 306. Fixed mirror306 is further optically coupled with image sensor 308. In particular,the numerally indicated elements in FIG. 3A composing the right sideoptical path of stereoscopic system 300, and constituting a rightoptical system, direct a right side image onto the right side of sensor308. Similarly, the left optical system of stereoscopic system 300 (notnumerally indicated) direct a left side image onto the left side ofsensor 308 via a left optical path.

Optical relay system 302 is an optical system for relaying anintermediate image 320 toward sensor 308. Relay system 302 can be aconstant magnification relay system, or can be configured to modify themagnification of a relayed image. An objective system (not shown)produces a right side intermediate image 320 on a focal plane 322,thereby enabling sensor 308 to detect the image. Dynamic mirror 304 andfixed mirror 306, together, form a folded optical path between relaysystem 302 and sensor 308. Dynamic mirror 304 and relay system 302 canbe translated along arrow 324 for changing the parallax or stereoscopicsystem 300. Thus, intermediate image 320 is relayed by relay system 302toward dynamic mirror 304, and from dynamic mirror 304 via fixed mirror306 toward the right side of sensor 308. Mirror 304 is dynamic to changethe parallax of the system. It can be a fixed mirror for systems notrequiring dynamic change of the parallax. In addition, other elementscan be designed to be dynamic instead or in addition to mirror 304.

With reference to FIG. 3B, stereoscopic system further includes a beamsplitter 310, optically coupled between mirror 306 and sensor 308, andan IR sensor 312. Beam splitter splits the relayed image such that it isdetected by both sensor 308 and sensor 312. It is noted that IR sensorcan be replaced by any other secondary sensor, such as a UV sensor, afocus sensor (as detailed herein below with reference to FIGS. 5A-5C), apolarized light sensor, and the like. Accordingly, beam splitter isadapted to the type of secondary sensor 312. For example, in case of anIR sensor 312, beam splitter 310 is a dichroic splitter separatingbetween visible light and IR light.

2.4 Robotic Arm Guidance

As detailed above, for example with reference to FIG. 1, the cameras ofthe microsurgery system of the disclosed technique are suspended inabove the operating area for imaging the operated area from a far,thereby freeing the OR from physical obstructions associated with priorart surgical microscopes. As further mentioned above, the cameras can bemounted on a mounting frame, which can be moveable, such as movingrobotic arm.

Reference is now made to FIG. 4, which is a schematic illustration of amounted microsurgery system, generally referenced 400, mounted on arobotic arm, constructed and operative in accordance with yet anotherembodiment of the disclosed technique. Mounted microsurgery system 400includes a microsurgery system 402, a robotic arm 404, and a supportpole 406. Microsurgery system 402 is mounted at the end of robotic arm404, which in turn is mounted on support pole 406.

Microsurgery system 402 is a system for acquiring image sequences of anoperated area, and for producing real-time magnified ROI sequencestherefrom allowing a user to perform a microsurgery procedure (e.g.,microsurgery system 100 of FIG. 1, or microsurgery system 200 of FIG.2). Robotic arm 404 is a mechanical arm including a plurality of linkscoupled by joints actuated by actuators, which allow for various motions(e.g., rotational joints and linear joints). Robotic arm 404 movesmicrosurgery system 402 for allowing microsurgery system to capturesequences of the operated area from a range of perspectives. The controlof robotic arm 404 would be detailed further herein below in thefollowing paragraphs. Support pole 408 supports robotic arm 404 (andmicrosurgery system 402). Thereby, microsurgery system 402 is suspendedabove the operated area.

Robotic arm 404 can be guided automatically according to the movementsof the user. Robotic arm 404 is coupled with the processing device ofmicrosurgery system 402 (not shown). For example, a tracker (e.g.,optical, electromagnetic and the like) is attached to the hand of theuser, for tracking its motions. The processing device guides robotic arm404 to move according to the motions of the hand of the user, such thatthe cameras of microsurgery system 402 (not shown) are imaging theoperated area. In accordance with another example, the tracker isattached to the head of the user. Robotic arm 404 follows the users headfor imaging the area that the user currently views. Microsurgery system402 of the disclosed technique can further incorporate safety mechanismsto avoid unwanted robot arm movements. For example, rapid movements arenot imitated by robotic arm 404, or an allowed motion box can bepredefined for robotic arm 404 (from which it cannot extend).

2.5 Autofocus

Reference is now made to FIGS. 5A, 5B and 5C, which are schematicillustrations of a focus-control system, generally referenced 500,constructed and operative in accordance with yet a further embodiment ofthe disclosed technique. FIG. 5A depicts the focus-control system. FIG.5B depicts the focal planes of the image sensor and the focus-controlsensor of the focus-control system of FIG. 5A, in case the imaged objectis out of the image sensor focus range. FIG. 5C depicts the focal planesof the image sensor and the focus-control sensor of the focus-controlsystem of FIG. 5A, in case the imaged object is within the image sensorfocus range.

Focus-control system 500 is a stereoscopic system including twosymmetric optical systems for acquiring two images from slightlydifferent perspectives. For the sake of brevity, only the right opticalsystem is indicated with reference numerals in FIG. 5A and would bedetailed herein below. However, the right optical system includes thesame elements and is operated in the same manner. Each of the opticalsystems (e.g., the right enumerated optical system and the leftun-enumerated optical system) is also referred to herein as a camerasystem. It is noted that the autofocus control mechanism describedherein below can be applied to a single camera (and not only tostereoscopic cameras). That is, the autofocus mechanism described belowfor the right optical system can operate independently for adjusting thefocus of single optical system.

Focus-control system 500 is configured to control the focus of anoptical system such that an imaged object (e.g., object 510 of FIGS. 5Band 5C) would be positioned within the focusing range of the imagesensor. Focus-control system 500 can be implemented in any imagingsystem having modifiable focus range. For example, focus-control systemcan be implemented within the microsurgery system of the disclosedtechnique.

Focus-control system 500 includes a lens 502, a beam splitter 504, animage sensor 506 and a focus-control sensor 508. Lens 502 is opticallycoupled with beam splitter 504, which in turn is optically coupled witheach of image sensor 506 and focus-control sensor 508. Focus-controlsystem 500 further includes a focus-modifying subsystem (not shown) anda controller (e.g., processing device 106 of FIG. 1, or processingdevice 206 of FIG. 2).

Lens 502 is an objective lens (or group of lenses) for producing animage of the object onto imaging sensor 506. Beam splitter 504 is anoptical element for splitting the light rays constituting the objectimage produced by lens 502, thereby producing two object images. Beamsplitter 504 directs one object image toward image sensor 506, and theother object image toward focus-control sensor 508. Image sensor 506 ispositioned coaxially with lens 502 and acquires the object imageproduced by lens 502.

Focus-control sensor 508 provides input to the controller forcontrolling the focus-modifying subsystem for modifying the focus ofsystem 500 of image sensor 506. Focus-control sensor 508 is tilted withrespect to the optical axis of lens 502 (i.e., more precisely tiltedwith respect to the folded optical axis of lens 502 after being foldedby beam splitter 504). Thereby, only a portion (e.g., a row) of focussensor 508 is in focus. By determining which row of focus sensor 508 isin focus, the controller can determine the desired focus characteristicsfor the image sensor (e.g., determine the desired focal plane and thedepth of field).

The controller can determine which row of focus-control sensor 508 is infocus by various methods, such as the row having the maximum intensity,the row associated with maximal gradients. Accordingly, the controllerdetermines the desired focus characteristics, and operatesfocus-modifying subsystem.

It is noted that in a stereoscopic system (composed of two cameras), itis important that the change in focus in both cameras is coordinated toprevent viewer fatigue and discomfort. That is, it is important thatboth cameras change focus at the same rate and focus on the same objectplane. Focus-control system includes a focus-control sensor for eachimage sensor, thereby allowing the controller to coordinate the focuscharacteristics of the image sensors. In accordance with an alternativeembodiment of the disclosed technique, only one of the image sensors(e.g., the left eye system) includes a focus-control sensor, and thecontroller adjusts the focus of both image sensors according to the dataprovided by the single focus-control sensor.

In the example set forth herein above with reference to FIGS. 5A-5C, anautofocus mechanism was coupled with each of a stereoscopic pair ofcameras. It is noted however that the autofocus mechanism can operate ina similar manner for a single camera as well. Additionally, theautofocus mechanism can be employed for controlling the focus of anylens system, whether coupled to a camera or not. That is, by directinglight focused by the lens system toward a tilted image sensor, anddetermining which portion of the image sensor receives a focused image,the autofocus mechanism can control the focus of the lens system.

2.6 Optical Tissue Penetration Module

In accordance with another embodiment of the disclosed technique, eachof the cameras of the microsurgery system of the disclosed technique canbe complemented with a tissue-penetration module. The tissue-penetrationmodule acquires an image of the subcutaneous tissues (e.g., imagepenetration of few millimeters) while the main image sensor acquires animage of the external tissues. Reference is now made to FIG. 6, which isa schematic illustration of a tissue-penetration system, generallyreferenced 600, for imaging subcutaneous tissues, constructed andoperative in accordance with yet another embodiment of the disclosedtechnique.

Tissue-penetration system 600 includes a microscope lens 602, a beamsplitter 604, a first image sensor 606, a 4f & deconvolution module 608and a second image sensor 610. The components of 4f & deconvolutionmodule 608 are shown in the magnified box, and include a first opticalassembly 612, a total internal reflector 614, a Digital Micro-mirrorDevice (DMD) 616 and a second optical assembly 618. Microscope lens 602is optically coupled with beam splitter 604. Beam splitter 604 isoptically coupled with both first image sensor 606 and with 4f module608. 4f module 608 is further optically coupled with second image sensor610.

Microscope lens 602 is a lens or a group of lenses (or other opticalelements) configured to receive light from a target area and to focusthe light, thereby producing an image of the focused area. For example,microscope lens 602 can be a lens positioned in front of the cameras ofthe imaging system of the claimed invention (e.g., imaging system 100 ofFIG. 1 or imaging system 200 of FIG. 2). Microscope lens 602 transmitsthe focused light toward beam splitter 604.

Beam splitter 604 splits the target area image received from microscopelens 602 (i.e., splits the light focused by lens 602) and directs afirst image toward first image sensor 606 and a second image toward 4fmodule 608. Thereby beam splitter 604 splits the optical axis of system600 into two optical branches. In particular, beam splitter 604 is adichroic beam splitter that directs visible light toward first imagesensor 606, and reflects IR light toward 4f module 408. That is,tissue-penetration system 600 includes a visible imaging channel and atissue-penetration channel which are branching at beam splitter 604.

First image sensor 606 is an image sensor for acquiring the image of thetarget area that is focused by microscope lens 602. Image sensor 606detects the image composed of the visible light transmitted by beamsplitter 604. Image sensor 606 is a high resolution image sensor similarto the image sensors of the cameras detailed herein above with referenceto FIGS. 1 and 2.

4f & deconvolution module 608 serves as an analog filter for filteringout spatial image frequencies. For example, when imaging a selectedsubcutaneous tissue layer, 4f module 608 filters out strong reflectionsfrom the skin, appearing as DC in frequency domain, and transmits toimage sensor 610 the high frequencies of the reflected from the tissueto be imaged. The components of 4f module 408 are depicted in themagnified box at the bottom right corner of FIG. 6, and would bedetailed further herein below.

Second image sensor 610 is an image sensor for acquiring an IR imagetransmitted by 4f module 608. The IR image can be composed of lightreflected from subcutaneous tissues at the target area and therebysecond image sensor 610 acquires an image of the subcutaneous tissues.The IR light reflected from the subcutaneous tissues is produced by anIR light source (not shown), and can be of various IR wavebands, suchas, Near IR (NIR). For example, the IR light can be of frequenciesbetween 700-1000 nm. In accordance with other embodiments of thedisclosed technique, frequencies between 1000-1700 nm can also be used.It is noted that lower frequencies (i.e., lower than 700 nm) penetratethe skin in a poorer manner. Higher frequencies (i.e., higher than 1700nm) might be complicated by means of optics and detectors. Additionally,the absorbance of higher frequencies in fluids (e.g., blood) is moresignificant.

In this manner, imaging system 600 simultaneously acquires a visibleimage of the external tissue layer of the target area and an image ofthe subcutaneous tissues. Imaging system 600 presents both images to theuser by employing a display. For example, the images can be overlaid,fused, or presented separately.

As mentioned above, 4f & deconvolution module 608 serves as analogspatial frequencies filter. The components of 4F module 608 are detailedin the following paragraphs. First optical assembly 612 is positionedsuch that the image of the target area focused by microscope lens 602and reflected by beam splitter 604 falls on a focal plane of firstoptical assembly 612. First optical assembly 612 produces a Fouriertransform of the image focused by lens 602 on the surface of DMD 616.That is, the focused image at an input plane of first optical assembly612 (i.e., located at the input focal length of optical assembly 612) istransformed into a frequency domain image at the output plane of firstoptical assembly 612 (i.e., located at the output focal length ofoptical assembly 612). In this manner, first optical assembly 612 servesas an optical transform system.

DMD 616 is composed of an array of separately controllable small mirrors(size of micrometers or tens of micrometers) that can switch between“on” and “off” states. Specifically, in the “on” state the mirrors ofDMD 616 reflects light toward second image sensor 610 (via reflector 614and second optical assembly 618), and in the “off” state it reflects thelight away from it. DMD 616 is positioned on a plane where opticalassembly 612 produces a Fourier transform of the image (i.e., at thesurface of DMD 616 the transformed focused image is presented in thefrequency domain). DMD 616 functions as an analog spatial filter. Thatis, mirrors of DMD 616 which are turned off, filer out respectivefrequencies of the transformed focused image of the target area. DMD 616filters out selected frequencies, for example, the DC of light reflectedfrom the skin layer so that it will not blur a subcutaneous image. Forexample, the mirrors at the center of DMD 616 are set to their off stateto serve as low pass filter. It is noted that, DMD 616 can be replacedby any other reflecting element capable of pattern changing.

Total internal reflector 614, reflects the light that was transmitted(i.e., not filtered out) by DMD 616 toward second image sensor 610.Total inner reflector 614 can be replaced by other reflectors that admitthe image toward DMD 616 and reflect the transmitted filtered image fromDMD 616 toward second image sensor 610. Second optical assembly 618transforms the frequency domain image transmitted from DMD 616 back intoimage domain of the target area. Specifically, second optical assembly618 focuses the back-transformed image on the surface of second imagesensor 610.

The focus distance of 4f module 608 can be varied for imaging differentlayers of subcutaneous tissues. The focus distance is varied by moving4f module 608, or elements thereof. Thereby, images of different tissueslayers are detected by second image sensor 610. The received images areblurred and composed of reflections from the different tissue layers.System 600 employs 3D deconvolution to reconstruct sharp images of thedifferent subcutaneous layers from the images detected by second imagesensor 610.

It is noted that the imaged target area is lighted for the purpose ofthe tissue-penetration imaging. In accordance with another embodiment ofthe disclosed technique, the light source is a polarized light source(linear, circular or other) to eliminate some specular reflections. Theimaging channel is polarized as well, in accordance to the light source,with different angle.

2.7 OCT

The cameras of the microsurgery system of the disclosed technique can becomplemented by an Optical Coherence Tomography (OCT) channel, and inparticular Fourier domain OCT. The OCT complemented system allows theuser to view in real-time an OCT image perfectly aligned to the stereoimage received by the microsurgery system. The OCT channel produces aset of images of various depths of subcutaneous tissues. Thus the OCTcomplimented microsurgery system allow presenting OCT images along with(e.g., overlaid on) the visible images of the external operated tissues.The OCT complimentary module is coupled to the microsurgery system via abeam splitter that splits the target area image received from microscopelens and directs a first image toward the image sensor of themicrosurgery system and a second image toward the OCT module.

Fourier Domain Optical Coherence Tomography (FDOCT) is an imagingtechnique that operates by collecting signals related to differentwavelengths of light, and using a mathematical relationship to generatean image. FDOCT extracts spectral information by distributing differentoptical frequencies onto an image detector via a dispersive element.Thereby the information of the full depth scan can be acquired within asingle exposure.

2.8 Parallax Control

As seen, for example, in FIG. 1, the microsurgery system of thedisclosed technique includes two cameras for acquiring stereoscopicimage sequences of the operated area. In accordance with anotherembodiment of the disclosed technique the parallax between the camerascan be adjusted. The adjustable parallax mechanism is employed forsituations in which the imaging angle between the cameras should bedynamically changed during an operation. Reference is now made to FIG.7, which is a schematic illustration of a microsurgery system, generallyreferenced 700, which parallax can be adjusted, constructed andoperative and accordance with yet a further embodiment of the disclosedtechnique. Microsurgery system 700 includes a pair of cameras 702 and704, a pair of fixed mirrors 706 and 708, and a pair of moveable mirrors710 and 712.

Cameras 702 and 704 are substantially similar to cameras 202 and 204 ofFIG. 2. Fixed mirrors 706 and 708 are reflectors fixed in place withrespect to cameras 702 and 704. Moveable mirrors 712 and 710 can bemoved along the X axis and can rotate at an angle θ (i.e., rotate aroundan axis perpendicular to the plane of FIG. 7). In this way, moveablemirrors 712 and 710 adjust the parallax between cameras 702 and 704, tocontrol stereopsis comfort. The rotation of moveable mirrors 710 and 712can be mechanically adjusted in accordance with the movement along the Xaxis. The movement in both ways (i.e., horizontal movement and rotation)can be set as a function of the object distance, the focus level, or auser interface selection. In accordance with another embodiment of thedisclosed technique, a light source can also be diverted using themoveable mirrors. For example, the illumination beam of a coaxial lightsource illuminating the LOS of the cameras is folded by the mirrors asis the LOS of the cameras.

In the example depicted in FIG. 7, moveable mirrors 710 and 712 aredepicted in two configurations, one depicted in solid line and anotherin dotted line. The solid depiction of moveable mirrors 710 and 712depicts the parallax for an object 714 positioned at a first distancefrom the cameras. The dotted depiction of moveable mirrors 710 and 712depicts the parallax for object 714 positioned at a second distance fromthe cameras. As can be seen, the parallax angle of the solid line isequal for the parallax angle of the dashed line, relating object 714solid and dashed appropriately.

2.9 DMD Light Source

In accordance with another embodiment of the disclosed technique, thelighting system can include a shutter module. A light source produces anillumination beam which passes through the shutter module on its way tothe target area (e.g., the operated area). The shutter module blocks (orat least attenuates) some portions of the illumination beam, therebycreating uneven illumination. In this manner, the shutter module allowsfor illuminating different portions of the target area in differentmanners.

Reference is now made to FIGS. 8A-8E, which are schematic illustrationsof a lighting system including a shutter module, generally referenced800, constructed and operative in accordance with yet another embodimentof the disclosed technique. FIG. 8A depicts a lighting system without ashutter module. FIG. 8B depicts a lighting system having a shuttermodule. FIG. 8C depicts a lighting system having a shutter module, whichlight passes through. FIG. 8D depicts a lighting system having areflective shutter module, positioned in the focal plane of an opticalmodule. FIG. 8E depicts a lighting system having a reflective shuttermodule, positioned out of the focal plane of an optical module.

With reference to FIG. 8A, lighting system 800 includes a light source802 (e.g., an optical fiber transmitting light from a light source, LEDsource or any other light source) and an optical module 804. Lightsource 802 provides an illumination beam to optical module 804, whichdirects the illumination beam toward target area 808. The illuminationbeam is represented by light beam 806A and 806B. Optical module 804 canfurther increase the output angle of the illumination beam, diffuse theillumination beam or shape it in other manners known in the art. A graph810 depicts the illumination level (the vertical axis) as a function ofthe location in the target area (i.e., the horizontal axis). As can beseen in Graph 810 of FIG. 8A, the illumination level is even across thetarget area.

With reference to FIG. 8B, a shutter module 820 is added to lightingsystem 800. Shutter module 820 is positioned between optical module 804and target area 808. Shutter module 820 receives the illumination beamand selectively attenuates (or blocks) portions of the illuminationbeam. Thereby, the microsurgery system of the disclosed technique canemploy lighting system 800, including the shutter module, forselectively controlling illumination levels of different portions of thetarget area. A graph 830 depicts the illumination level (the verticalaxis) as a function of the location in the target area (i.e., thehorizontal axis). As can be seen in Graph 830 of FIG. 8B, theillumination level of different portions of the target area is uneven.That is, some portions receive higher levels of illumination, and someportions don't receive any illumination at all.

In this manner, the shutter module of the lighting system allows forselectively adapting the illumination level of different portions of thetarget area to various applications. For example, a highly reflectivearea of the target area (e.g., covered with a mucosal layer) can receivelower illumination levels to avoid blinding or to improve the dynamicrange of the cameras of the microsurgery system.

With reference to FIG. 8C, shutter module 820 (depicted in a dottedline) includes a shutter array 822 and optical elements 824. Shutterarray 822 can selectively attenuate different spatial portions of theillumination beam passing therethrough. Optical elements 824 receive theselectively-spatially-attenuated illumination beam and direct it to thetarget area. Optical elements 824 can shape theselectively-spatially-attenuated illumination beam, for example, byincreasing the output angle of the beam, diffusing the beam, and thelike.

With reference to FIG. 8D, the shutter module includes a reflectiveshutter array 822, optical elements 824. Reflective shutter array 822can be for example, a DMD, or another pattern reflector. Reflectiveshutter array 822 can selectively reflect different spatial portions ofthe illumination beam toward optical elements 824 or deflect them inanother direction, such that portions of the illumination beam would notreach the target area. The shutter module can further include a blackscreen 826 toward which unwanted portions of the illumination beam canbe directed, and for preventing outside light from reaching opticalelements 824. Optical elements 824 receives the reflected illuminationbeam (i.e., those portions which were selectively reflected towardoptical elements 824 by reflective shutter array 822) and direct it tothe target area. In the example set forth in FIG. 8D, reflective shutterarray 824 is located at the focal plane of optical module 802.

With reference to FIG. 8E, reflective shutter array 824 is located outof the focal plane of optical module 802, such that shutter array 824receives a collimated (or semi-collimated) illumination beam, andselectively reflects spatial portions of the illumination beam towardoptical elements 824.

3 Optional HMD Structure

The processing device of the microsurgery system of the disclosedtechnique (e.g., microsurgery system 200 of FIG. 2) provides imagesequences to the HMD, possibly including overlaid data and symbols. TheHMD can include several display components, for example, for displayinga central high resolution image and a peripheral lower resolution image(as would be detailed further below with references to FIGS. 9A-9C), theprocessing device provides the necessary image or control instructionsto each display component. The HMD can include display components suchas micro-displays, scanning mirrors, Digital Micro-mirror Device (DMD),and the like.

A see-through HMD may be used in some embodiments, thus allowing imagesequences to be superimposed on a real-world view (though magnifiedimages are not superimposed on an unmagnified real-world view). Thesee-through HMD enables any of the following exemplary applications:

-   -   Switching between the projected video to real world by varying        the see-through opacity.    -   Maintaining semi-transparency in the see-through opacity and by        that showing real world and video.    -   Overlaying video on the real world, and by so providing        augmented reality.

In accordance with another embodiment of the disclosed technique, thetransparency of the display can be controlled. A shutter mechanismcoupled with the display can block (or attenuate) the outside sceneimage passing through the see-through display. When the shutter is openthe projected image (e.g., acquired by the cameras) is overlaid on theoutside image. When the shutter is closed, the outside image is blocked,and the viewer sees only the projected image. By closing the shutter,the contrast of the projected image is increased. The shutter can beeither mechanical or electronic, or any other shutter type. The shuttercan be manually or automatically activated. For example, the user canturn the shutter on and off (or control the degree of attenuation of theoutside image) by an interface, such as a control button, via voiceactivation, or via head motion activation. For instance, when the userturns her head by more than 25 degrees (as determined by the tracker),the shutter is opened to allow the user to view her surroundings. Theshutter attenuation can change gradually with the movements of the headof the user, or change abruptly at a predefined threshold (i.e., stepfunction). The transparency change can be made on part of thesee-through display or all of it. Transparency may be adjusted accordingto user manual selection and/or ambient light thresholds.

In accordance with another embodiment of the disclosed technique thedisplayed images of the HMD are focused to infinity. The focus toinfinity provides the viewer relaxed effort for the eye and is lessexhausting. In accordance with yet another embodiment, in case the HMDis a see-through HMD, and as the real world objects are not located atinfinity (but within the OR), the focus of the HMD is set to the objectsdistance. The HMD can utilize a dynamic focus mechanism, setting theprojected image focus distance to the viewer eye focus distance (or tothe distance of the object that the viewer sees).

The transparency change of a see-through HMD can be made using passiveor active coating or pads on the see-through display. The coating orpads are placed on a display element which is in the user line of sight.For example, it can be placed on a visor, a combiner, a waveguide or anyother optical element used for the see-trough display. Passive coatingcan be activated to decrease the see-through display transmission byusing Ultraviolet (UV) or IR illumination. Active coating can beelectrically activated to decrease transmission.

The HMD of the disclosed technique produces high quality imagesequences, which must be acceptable for the user (when compared to theimage viewed through the eyepiece of a conventional surgical microscope.Put another way, the optical parameters of the HMD should be good enoughto satisfy human vision parameters. The FOV of human vision is wide, yetthe human IFOV (or visual acuity) varies with the location of the imageon the retina. In particular, there is a relatively small area of theretina (i.e., relatively small FOV) with improved visual acuity. Thisarea of the retina is called the fovea, and covers about two degrees ofthe FOV. When drawing away from the fovea the visual acuity degrades. Ahuman viewer will not notice improvement in resolution, or have theability to see more details, by displaying images that allow for smallerIFOV than that of the human vision. Therefore, images projected on theperiphery of the retina surrounding the fovea, can be of reducedresolution (with respect to the images projected on the fovea), withoutcompromising the acuity of the image perceived by the observer.

It is common to refer the measurement of the limiting visual acuity onshapes, gratings, points etc. For a normal young healthy person, havinggood sight, the eye can identify two small points on uniform background(where the points are black and the background is white) when the angleseparating them is larger than 1 arcmin (1 arcmin, or minute of arc,equals roughly 0.000291 rad). When a healthy person observes gratingpattern (white bar next black bar, with repeating pattern), the eye canidentify the bars as long as the angle between them is larger than 2arcmin. Many factors influence the visual acuity and may degrade it—likethe scene brightness, distance of image from the center of fovea, theage of person, the contrast of target, stability of the image etc. Thepupil diameter also effects the visual acuity significantly (effects thediffraction of the eye and the optical aberrations). Taking intoconsideration all of the parameters effecting visual acuity it is commonto say that a healthy human visual acuity is in the range of 1 arcmin to2 arcmin (0.000291 to 0.000582 rad).

Reference is now made to FIGS. 9A, 9B and 9C, which are schematicillustrations of an HMD, generally referenced 900, for displaying a highresolution image to the fovea and displaying a lower resolution image tothe periphery of the eye of the user, constructed and operative inaccordance with yet another embodiment of the disclosed technique. FIG.9A depicts HMD 900. FIG. 9B depicts the fovea image the periphery imageand the combined image of HMD 900 of FIG. 9A. FIG. 9C depicts a relativevisual acuity scheme of a human eye.

With reference to FIG. 9A, HMD 900 is an exemplary HMD providing varyingresolution images adapted to the varying IFOV of the human eye withinits FOV. In particular, HMD 900 displays a high resolution image to thefovea, and displays a lower resolution image to the peripheral portionsof the eye of the user. HMD 900 is a dual-eye HMD including a pair ofmicro-display systems, one for each eye. Each micro-display systemincludes a peripheral display 902, a fovea display 904, a fixed mirror906, a scanning mirror 908, an optical combiner 910 and an eye trackingcamera 912. Peripheral display 902 is optically coupled with opticalcombiner 910. Fovea display 904 is optically coupled with opticalcombiner 910 via fixed mirror 906 and scanning mirror 908.

Each of displays 902 and 904 can be any micro-display, such as an LCD,an Organic Light-Emitting Diode (OLED) or a Liquid Crystal on Silicon(LCOS). Additionally, each display can include additional opticalelements, such as Digital Micro-mirror Device (DMD), a Digital LightProcessing (DLP), scanning mirrors or any other method. Peripheraldisplay 902 projects a peripheral image, and fovea display 904 projectsa fovea image, both received from a processing device of a microsurgeryimaging system (e.g., system 100 of FIG. 1 or system 200 of FIG. 2).Peripheral display 902 and the fovea display 904 are combined viaoptical combiner 910. The peripheral image, the fovea image and thecombined image are detailed further herein below with reference to FIG.9B.

The FOV of Fovea display 904 is narrow with respect to the FOV ofperipheral display 902. However, the resolution of the fovea image islarger than that of the peripheral image. Put another way, the IFOV offovea display 904 is smaller than that of peripheral display 902. Thefovea image is moved according to the LOS of the viewer, as detected byeye tracking camera 912. For example, the fovea image is shifted byusing a rotating mirror (e.g., actuated by MEMS). The rotating mirror(e.g., rotating around 2 Axes) is enslaved to the LOS of the viewer. Thefovea image sequences directed to the fovea are substantially centeredaround the tracked LOS of the user. It is noted that HMD 900 can includeany other functionality, or combination of functionalities, as detailedherein above with reference to HMD 209 of FIG. 2 and with reference toany HMD detailed in this application.

With reference to FIG. 9B, a peripheral image 920 and a fovea image 922are combined into a combined image 924. As can be seen in FIG. 9B, foveaimage 922 is smaller than peripheral image 920 (i.e., occupies a smallerportion of the combined image displayed to the user). On the other hand,the resolution (or acuity) of fovea image 922 is larger than that ofperipheral image 920. Specifically, the image resolution of fovea image922 (and the distance of the fovea display from the eye) allows an IFOVsmaller or approximately equal to that of the human fovea, or at leastcomparable thereto (i.e., better angular resolution than that of thehuman eye). Similarly, the image resolution of peripheral image 924 (andthe distance of the peripheral display from the eye) allows an IFOVsmaller than that of the human peripheral retinal areas, or at leastcomparable thereto.

For example, in accordance with one embodiment of the disclosedtechnique, the processing device of the microsurgery system producesfovea image sequences allowing for IFOV smaller than 0.000592 radians.In accordance with another example, the FOV within which the fovea imagesequences are viewed can be at least 2°.

To achieve better transition between the two superimposed images somesmoothing can be done in the stitching area. For example, in the edgesof fovea image 922, the resolution can be degraded monolithically (e.g.,using image processing smearing) down to the resolution of peripheralimage 920. Thereby, the combined image looks more natural.

As can be seen in FIG. 9C, displaying two grades of images, a high gradeto the fovea and a lower grade to the periphery, will not compromise theacuity of the image perceived by the user. This is because the highgrade image projected on the fovea allows for IFOV comparable with (orbetter than) that of the user in the fovea, and the lower grade imageprojected on the periphery also allows for IFOV comparable with (orbetter than) that of the user in the peripheral areas of the retina. Inthe example set forth in FIG. 9C, the high grade image is projectedwithin 10° of the fovea, and the lower grade image is projected ontoretinal areas which are further than 10° from the fovea.

3.1 Dynamic Eye Piece Parallax Control

In accordance with another embodiment of the disclosed technique, wherethe display (e.g., HMD 108 of FIG. 1 or HMD 208 of FIG. 2) includes aseparate display for each eye of the user, the controller (i.e., theprocessing device) can adjust the display parallax to correspond to theuser comfort. Prior art conventional surgical microscopes include fixedeyepieces, which are fixed in space. The fixed eyepiece compels the userto fix her head for long time periods in a stressed position. Minor headmovements may cause image degradation starting with image vignette,blurring and complete loss of image.

Reference is now made to FIGS. 10A and 10B, which are schematicillustrations of a display system, generally referenced 1020, havingadjustable eyepieces, constructed and operative in accordance with yet afurther embodiment of the disclosed technique. Display system 1020 is adisplay having eyepieces (and is not an HMD). Thus, display system 1020can be used for any system having eyepieces, such as a microscope havingeyepieces.

With reference to FIG. 10A, a user views a displayed image (not shown)via eyepiece 1004. Specifically, the user directs her eye 1002 towardeyepiece 1004. The LOS of eye 1002 is indicated by 1006. The opticalaxis of eyepiece 1004 is indicated by 1008. For the user to view thedisplayed image, LOS 1006 should be substantially coaxial with opticalaxis 1008, and eye 1002 should be close enough to eyepiece 1004.

The adjustable eyepiece system of the disclosed technique aligns itselfwith the eyes of the user when the user places her head within apredefined motion box. The motion box is defined as the area that islimited by the range of eyepiece motion or by the detection range of ahead or an eye tracker. With reference to FIG. 10B, adjustable eyepiecesystem 1020 includes an eyepiece support frame 1022 and a pair ofeyepieces 1024. Eyepieces 1024 are incorporated into eyepiece supportframe 1024. Eyepiece support frame 1022 further supports the opticalchannels leading to eyepieces 1024. Each optical channel relays to eachof eyepieces 1024, a respective image to be displayed, and can furtherrelay an outside scene image, onto which the display image is overlaid.

Eyepiece support frame 1022 allows adjusting the eyepieces position bymoving along three axes −X, Y and Z, as seen in the Figure. Thereby, theposition of eyepieces 1024 can be adjusted to the position of the eyesof the user. Additionally, eyepiece support frame 1022 allows directingeyepieces 1024 by rotating at angles θ, ϕ and ω, as seen in the Figure.Thereby, the optical axes of eyepieces 1024 can be adjusted to the LOSof the user. Further additionally, eyepiece support frame 1022 allowsvarying the Intermediate Pupil Distance (IPD) of eyepieces 1024, foradjusting it to the IPD of the user.

The alignment of eyepiece support frame 1022, and thereby of eyepieces1024, is controlled according to the position and orientation of the eyeof the user as determined by the tracker. In accordance with oneembodiment of the disclosed technique, the eyepiece alignment isperformed once at the beginning of the surgical operation.Alternatively, in accordance with another embodiment, the head of theuser is continuously tracked, and the eyepieces are aligned accordinglythroughout the procedure. In the dynamic adjustment of the eyepieces,limitations can be defined for preventing the system from movingrapidly. For example, when the user moves her head sideways by an extentexceeding a threshold (e.g., to see other things in the OR), system 1000does not move the eyepieces with the head of the user.

For moving and directing eyepieces 1024, eyepiece support frame 1022 canbe a motorized stage, a gimbal, a robotic arm and the like. Supportframe 1022 moves and rotates eyepiece 1024 according to instructionsfrom a controller. The controller receives input respective of the headposition and orientation from the head tracker, and can additionally oralternatively receive input respective of the eye position andorientation from the eye tracker. For example, the eye/head position andorientation can be determined using proximity sensors, cameras,structured illumination, time-of-flight, placing a marker on the userhead or eyes (e.g., visual, magnetic or RF marker) or any other method.

Adjustable eyepiece system 1000 can be activated automatically based onthe sensors installed in the system or based on user activation. Theuser can activate using voice, keyboard, joystick (of any type),head/eye gesture, control panel etc. The eyepiece can be a non-seethrough based on micro-display (e.g., OLED, LCOS, LCD or any other). Inthis case a micro display is coupled to relay optics projecting theimage to the user eyes. This can be made using mirrors to fold theoptics for ergonomics improvement or obstruction prevention. Theeyepiece can be a see-through based on optical combiner, waveguide orprojection optics.

In accordance with an alternative embodiment of the disclosed technique,adjustable eyepiece system 1000 aligns eyepieces 1024 to a referenceplane, which is orthogonal to the face of the user (as determined by thehead tracker). Thus, dynamic eyepiece system 1000 eliminates differentalignment of the eyepiece when the user eyes are directed to differentplaces.

4 Trackers & LOS

Referring back to FIG. 2, in some embodiments of the disclosedtechnique, HMD 208 is coupled with tracker 218 (e.g., tracking the head,the eye, or both). Tracker 218 tracks the LOS of the user (i.e., alsoreferred to as the gaze direction). For example, tracker 218 is an eyetracker directly tracking the user LOS, or is a head tracker trackingthe head of the user and accordingly determining the viewer LOS. The LOScan be calculated, for example, for three coordinates (e.g., azimuth,elevation and rotation-orientation) or for six coordinates (position andorientation).

Processing device 206 receives the gaze direction from tracker 218 andaccordingly determines the ROI of the operated area respective. That is,the tracked gaze direction serves as an input indicating the ROI, andaccordingly processing device 206 produces ROI image sequences from theacquired operated-area sequences by cropping the respective portion ofthe ROI and resizing the image sequences to fit HMD 208.

Tracker 218 can be, for example, an optical tracker employing at leastone image sensor and at least three optical markers. For instance, thesensor can be mounted on the head of the user and the markers on the bedof the patient. Alternatively, the sensor is mounted on the bed of thepatient (or at another place in the OR), and the markers are mounted onthe head of the user. Further alternatively, one sensor is mounted onthe head and one in the OR and some markers are mounted on the head andsome in the OR. Alternatively, tracker 218 can be electromagnetictracker, ultrasonic tracker, electromechanical tracker (e.g.,Micro-electro-mechanical System-MEMS-gyroscopes), and any other trackingmechanism.

Tracker 218 can either calculate the user LOS, or gather data enablingprocessing device 206 to calculate the LOS. As mentioned above, the userLOS can be employed as input for indicating which region of the operatedarea is of interest to the user, thereby allowing processing device todetermine the ROI, and accordingly to produce respective ROI imagesequences. The LOS (and possibly the position or location of the userhead) can be employed for other (or additional) functions andapplications of microsurgery system 200, as would be exemplified in thefollowing paragraphs.

Tracking the viewer LOS enables processing device 206 to createspace-stabilized objects within the display. In other words, HMD 208utilizes the tracked LOS for constantly presenting symbols, informationand images, in the same location within the field of regard of the user.The space-stabilized objects can include the image sequences fromcameras 202 and 204, and any further data that may be useful to theuser, such as medical history, previously obtained medical imaging data(e.g., CT or MRI scans), current patient vital statistics (e.g., pulseand blood pressure), and the like. These may be placed at user-definedspatial locations. For example, looking at 45° to the left, the user cansee the patient's last CT scan, looking forward gives the ROI magnifiedimage sequences, looking down allows to see the patient through thesee-through display, and looking up provides the time display. For manyusers, the ability to provide a stable image helps to prevent nausea.

Tracker 218 can be employed for controlling the brightness of asee-through display. For example, when the user's head is in onedirection the transparency is low, so the projected image contrast ishigh. When the head moves to another direction, the transparency ishigh, so the user can view other portion of the OR clearly, therebyincreasing the situational awareness of the user. The display brightnessreduction can also be used to improve the contrast of a backgroundimage.

According to the LOS of the viewer a see-through HMD can focus theprojected image according to the real world object distance. Withadditional mechanism (e.g., a camera) and the LOS of the viewer the HMDcan detected the distance to the object and focus accordingly. Thisfocus mechanism will prevent fatigues to the eye (due to changes infocus between the display and the real world).

Tracker 218 can be used as an input interface for controlling variousfunctions. Tracker 218 can be employed for controlling the digital imagemagnification. Zoom control can be performed by moving the head forwardand backward, setting the “zoom in” and “zoom out” function. Tracker 218can be employed for controlling the movements of the cameras (in casethe cameras are moveable). For example, the cameras are enslaved to thehead motions.

An eye tracker can be used to locate the exact eye LOS relative to HMD208. For example, in case HMD 208 displays a central high resolutionimage and peripheral lower resolution images, as detailed herein belowwith reference to FIGS. 9A-9C, the central high resolution image isprojected along the eye LOS.

5 Applications

Referring back to FIG. 2, the operated-area image sequences can be usedfor different applications, as would be exemplified in the followingparagraph. The entire data can be saved for late debrief. During theoperation, a plurality of users can each select a different ROI (e.g.,different coordinates and magnification). Processing device 206 may beconfigured to apply different image processing or video processingalgorithms to different ROI sequences presented to different users. Inthis manner, each user may select his ROI, and receive a tailoredprocessed ROI image by applying the image processing algorithms or anyother operation applied to the user-specific ROI sequence. This isimportant, as an example, for complicated surgeries, where severalsurgeons are operating at the same time. Not only surgeons can use thedifferent ROI sequences, but also students, nurses or other staffmembers, and users which are not in the same operating room. Some ROIsequences can be produced for processing device 206 itself, and not fora human user. For example, the user marks an area of interest whichprocessing device 206 tracks for determining whether there is blood flowor other defined event. The user can mark different ROIs withbookmarking. In this case the user can return to the bookmarked ROI.Bookmarked ROIs can include magnifications change and XY translations.

Processing device 206 can further process the acquired image sequences.For example, processing device 206 can combine the image sequences intoa stereoscopic sequence or a 3D video. Processing device 206 can performother image processing operations, such as image correction (e.g., fixedpattern noise corrections, color corrections, distortion corrections,histogram enhancement and the like), adding markers on relevant imagefixtures, tracking objects, emphasizing objects and the like, overlayingmonitoring data or patient history data, fusing the image sequences withdata gathered by other imaging devices (e.g., CT and MRI).

Processing device 206 can generate different markers of interestfeatures on the projected image sequences. The markers can be employedto specify features to address, such as medical tools and physiologicalsites. Additionally, processing device 206 can generate important ORequipment data and patient history information to present on theprojected display of HMD 208. For example, processing device 206 canoverlay monitoring data or patient history data, or fuse the acquiredimage sequences with other imaging device like CT, MRI and the like. Thedata can be presented on the displayed sequences or in the field ofregard.

Another processing application of processing device 206 is generating a3D model of the object. It can be made at real-time for fixed cameras ornon-real-time for moving cameras. As example, the use for thisembodiment can be render of 3D model of the head and brain forneurosurgery (visible area by the cameras). The 3D model can begenerated from stereoscopic imagery. In this way a 3D data base on theimaged object is made by using 2 or more fixed cameras imaging the sameobject from different angles. Another method for 3D image reproductionfrom 1 camera or more can be time based. The camera (or cameras) ismoved to different locations around the subject head. The images aresaved in the memory unit as well as their position when capturing theimages. Processing device 206 uses the images to generate 3D model ofthe head and brain based on the captured images from different angles.An exemplary algorithm for such 3D model can be implemented using Radontransform or standard stereoscopic algorithm. This model can be usedduring the surgery to help the surgeon navigate or improve the 3Dorientation. The 3D database can also be used for non-display purpose,such as image correlation, tracking and the like.

Another processing application of processing device 206 is providingguidance to the user. Processing device 206 produces and displays a pathfor a surgical tool to a selected destination. The path can be generatedautomatically, manually or by a combination of both. The path isproduced by employing the 3D database created from images received fromthe cameras. Based on the 3D images the microsurgery system of thedisclosed technique tracks the tool and guides the surgeon to thedesignated direction. System 200 can generate warning when the surgeondoes not move the tool in right direction or gets close to sensitiveareas.

Communication interface 220 is employed for communicating with a remotesite 222. For example, processing device 206 can receive data such asthe medical history of the patient from the patient's regular clinic.Processing device 206 can send the captured video images to a remotesite at which an expert is positioned so that the expert can counsel themedical staff in real-time.

5.1 Virtual Depth of Field

Depth of Field (DOF) of an optical system is a function of manyparameters, such as the focal length and the F number. Objects withinthe DOF are viewed sharply as focused objects, and objects outside theDOF may be blurred. In conventional imaging systems as known in the art,the user may adapt the DOF for her needs. For example, the user candesign an optical system having a large DOF in order to focus as manyfeatures as possible. Conversely, the user may design a system having asmall DOF to allow the user to focus her attention to limited featuresin the scene. As mentioned above, the microsurgery system of thedisclosed technique acquires operated-area image sequences of theoperated area. The microsurgery system can present different cropped andresized portions of the operated-area sequences (i.e., ROI sequences) todifferent viewers. Each user may want to focus on different objectswithin the displayed image (i.e., each user may require a differentDOF).

As detailed above with reference to FIG. 2, microsurgery system 200includes two cameras 202 and 204 and processing device 206. Cameras 202and 204 capture image sequences of an operated area from two differentperspectives to be displayed to each eye, providing 3D imaging.Processing device 206 can calculate the depth data of various features(or objects) in the 3D image. Using the calculated depth data system 200can create a virtual DOF (i.e., a sub-region within the real opticalDOF) by virtually rendering different parts of the image such thatfeatures within the virtual DOF appear in focus, and features outsidethe virtual DOF appear as blurred, or are otherwise rendered to be seenas background. As an example, in cornea surgery, microsurgery system 200can blur all the areas in the image which are not the user tools and thethin cornea.

Processing device 206 can determine depth data of different features inthe images acquired by cameras 202 and 204, in real-time, by employingtechniques, such as stereo imaging algorithms, structured lighttechniques, time of flight algorithms, and the like. Processing device206 can determine the depth data of features in the images, not inreal-time, by employing techniques, such as by changing the focus onconsecutive images and labeling the distances of the features.

The virtual DOF (i.e., the range of distances at which objects wouldappear as in focus, or the objects of interests which would appear as infocus) may be set in various ways, such as manually; automatically bythe microsurgery system according to a predefined goal, or according toa value that is set according to a cuing process performed by the user;automatically by a learning process that identifies the existingmotion-box of objects in the scene when the system is performing itsnormal functions, or during a specified learning period.

Once the virtual DOF is set, objects (or features) within the imagepresented to the user can be manipulated according to their respectivedepth, and the set virtual DOF. The manipulations are based on imageprocessing techniques. For example, objects outside of the virtual DOFcan be blurred, blackened, erased, the transparency of objects outsidethe virtual DOF can be increased, and the like. In general, any visualmanipulation can be employed on the objects for focusing the attentionof the user to the objects within the virtual DOF and for rendering theobjects outside the virtual DOF to appear as background or asinsignificant.

In accordance with another embodiment of the disclosed technique,surgical tools can be displayed in focus even if they are located out ofthe selected virtual FOV. This is done by tracking the tools and keepingthem in focus, regardless of their relative location with respect to thedefined virtual DOF.

The virtual DOF of the disclosed technique can be employed for negatingsome of the problems associated with stereoscopic imaging ofmicrosurgeries. For example, the difference depth of an object in thedifferent cameras can cause hyper-stereopsis on parts of the image. Thedepth variation of objects may cause difference parallax (or offset) andunnatural stereo image, and may cause squinting, headaches and fatiguefor the user. The virtual DOF decreases these stereo issues. The user(or the system) defines the objects of interest in the scene, and theremaining objects are blurred to prevent stereo-related fatigue.

Reference is now made to FIGS. 11A, 11B, 11C and 11D, which areschematic illustrations of a virtual depth of field scheme forpresenting to a user a selected virtual depth of field, operative inaccordance with yet another embodiment of the disclosed technique. FIG.11A presents an image of three objects. FIG. 11B presents the image ofFIG. 11A in which the first object is within the virtual depth of fieldand the second and third objects are not. FIG. 11C presents the image ofFIG. 11A in which the second object is within the virtual depth of fieldand the first and third objects are not. FIG. 11D presents the image ofFIG. 11A in which the third object is within the virtual depth of fieldand the first and second objects are not.

With reference to FIG. 11A, an image 1100 includes a first object 1102,a second object 1104 and a third object 1106, depicted as a square,circle and triangle, respectively. A user viewing image 1100 may want tofocus her attention to one of the objects. In conventional imagingsystems as known in the art, the user would adjust the focus of theimaging system such that the object in which she is interested is infocus and the rest of the image may be blurred. That is, the user wouldadjust the focus of a conventional imaging system such that the objectof interest is within the depth of field of the conventional imagingsystem. The microsurgery system of the disclosed technique can produce avirtual depth of field, such that the object of interest would be infocus and other objects within the actual, optical, DOF would beblurred. Put another way, the microsurgery system of the disclosedtechnique would blur all objects in the image, except the object ofinterest, thereby, focusing the user attention to the object of interestand avoiding confusion and disturbing visual stimulations.

With reference to FIG. 11B, first object 1102 is presented in focus(i.e., depicted as solid line), and second and third objects 1104 and1106 are presented as blurred (i.e., depicted as dotted lines). Withreference to FIG. 110, second object 1104 is presented in focus (i.e.,depicted as solid line), and first and third objects 1102 and 1106 arepresented as blurred (i.e., depicted as dotted lines). With reference toFIG. 11D, third object 1106 is presented in focus (i.e., depicted assolid line), and first and second objects 1102 and 1104 are presented asblurred (i.e., depicted as dotted lines).

As mentioned above, each user can be presented with a different imagewith a different virtual DOF. For example, a first surgeon would viewthe image of FIG. 11B in which object 1102 is within the virtual DOF,and a second surgeon would view the image of FIG. 11D in which object1106 is within the virtual DOF. Thereby, each user focuses its attentionon relevant image features, such as the tissues she is operating on, andher surgical tool.

6 Additional Inputs for Display

Referring back to FIG. 2, medical imaging source 210 provides medicalimaging data to processing device 206. The medical imaging data can beoverlaid on the image sequences provided by cameras 202 and 204. Forexample, medical imaging data can be obtained by CT or MRI scans,ultrasonic imaging, X-ray imaging, infrared imaging, fluoroscopicimaging, and the like. Medical file data source 212 provides processingdevice 206 with data from the medical file of the patient. Thereby, theprocessing device can present to the medical staff the history data ofthe patient. Physiological measures source 214 can include varioussensors for determining various physiological measures of the patient,such as the vital signs (e.g., body temperature, pulse rate, bloodpressure and respiratory rate), and other physiological measures such asEEG, and the like. Processing device 206 may be further communicatingwith additional units within the OR (e.g., microscopes, laparoscopes,endoscopes).

It is noted that the microsurgery system described herein above can beemployed for every micro-medical procedure in an operating room or inany other treatment room. Some examples of such procedures includeimaging in the area of orthopedic micro-surgery, gynecologicalmicro-surgery, otolaryngology, neurosurgery, oncologic micro-surgery,pediatric, oral and maxillofacial, plastic micro-surgery, and the like.In the above description, another embodiment is an example orimplementation of the invention. The various appearances of “oneembodiment”, “an embodiment” or “some embodiments” do not necessarilyall refer to the same embodiments. Although various features of theinvention may be described in the context of a single embodiment, thefeatures may also be provided separately or in any suitable combination.Conversely, although the invention may be described herein in thecontext of separate embodiments for clarity, the invention may also beimplemented in a single embodiment.

The invention claimed is:
 1. A microsurgery system comprising: a headmounted display (HMD) configured to display to a user in real-timemagnified image sequences of a region of interest (ROI) of an operatedarea; at least one camera configured to acquire operated-area imagesequences of said operated area, a size of said operated area beinglarger than a size of said ROI, said at least one camera being suspendedabove said operated area and being mechanically and opticallydisconnected from said HMD; a memory configured to store saidoperated-area image sequences; and a processing device coupled with saidHMD, said at least one camera and with said memory, said processingdevice being configured to receive an input indicating said ROI, andconfigured to produce said magnified image sequences of said ROI fromsaid operated-area image sequences; wherein said HMD displays saidmagnified image sequences of said ROI to said user at an angularresolution which is equal to or smaller than the angular resolution of ahuman eye.
 2. The microsurgery system according to claim 1, wherein saidprocessing device is configured to grab a full image out of a sensor ofsaid at least one camera, and to digitally crop and resize said ROI. 3.The microsurgery system according to claim 1, wherein said processingdevice is configured to grab said ROI out of a sensor of said at leastone camera by at least one of the list consisting of: addressing onlypixels corresponding to said ROI; and under-sampling said sensor.
 4. Themicrosurgery system of claim 1, further comprising a tracker configuredto track a line of sight (LOS) of said user, wherein said processingdevice is configured to determine said ROI according to said LOS.
 5. Themicrosurgery system according to claim 4, wherein said tracker is an eyetracker.
 6. The microsurgery system according to claim 4, wherein saidimage sequences of said ROI are modified at least partially based onspatial movements of said HMD as detected by said tracker.
 7. Themicrosurgery system according to claim 1, wherein said at least onecamera is configured to carry out automatic focus based on said ROI. 8.The microsurgery system according to claim 1, further comprising anarray of controllable light sources facing said operated-area, andwherein said controllable light sources are dynamically adjusted basedon a dynamic analysis of an image histogram of said image sequences toachieve at least one effect selected from: reduce specular reflections;and increase the dynamic range of the captured scene by of said at leastone camera.
 9. The microsurgery system according to claim 1, whereinsaid HMD includes a first region and a second region, an angularresolution of said first region being numerically smaller than 0.000582radians and an angular resolution of said second region beingnumerically larger than that of said first region, and wherein saidfirst region has a field of view of at least 2° and is substantiallycentered around said LOS of said user.
 10. The microsurgery system ofclaim 1, wherein said processing device crops a ROI portion of saidoperated-area image sequences respective of said ROI, and resizes saidROI portion for producing said magnified image sequences of said ROI.11. The microsurgery system of claim 1, wherein said at least one cameraincludes two image sensors, and further includes a folding opticalsystem located in front of said two image sensors, said folding opticalsystem including at least a pair of fixed mirrors and a pair of moveablemirrors, wherein at least one of said moveable mirrors is configured tomove away and toward another one of said fixed mirrors.
 12. Themicrosurgery system of claim 1, wherein each of said movable mirrors isconfigured to move toward and away from another one of said moveablemirrors, and wherein each of said movable mirrors is configured torotate about an axis perpendicular to an optical axis of saidmicrosurgery system and perpendicular to an axis extending between saidmovable mirrors, thereby said movable mirrors enable said microsurgerysystem to adjust a parallax of an object in an image acquired by a firstone of said image sensors and an image acquired by a second one of saidimage sensors.
 13. The microsurgery system of claim 1, wherein said atleast one camera includes an image sensor, a secondary sensor and a beamsplitter directing light from said operated area toward said imagesensor and toward said secondary image sensor.
 14. The microsurgerysystem of claim 1, further including a robotic arm, wherein said atleast one camera is mounted on said robotic arm.
 15. The microsurgerysystem of claim 14, wherein said robotic arm is enslaved to a LOS ofsaid HMD.
 16. The microsurgery system of claim 14, wherein said roboticarm is enslaved to a medical tool operated by said user.
 17. Themicrosurgery system of claim 1, further comprising a focus-control 2Dsensor array configured to receive an image captured by a selected oneof said at least one camera, said focus-control sensor being tilted withrespect to an optical axis of said at least one camera, wherein saidprocessing device is configured to determine a location in saidfocus-control sensor in which an image is focused, and accordingly toadjust focus characteristics of said selected one of said at least onecamera.
 18. The microsurgery system of claim 1, further comprising asubcutaneous imaging module including an infrared (IR) light source, afirst optical transform system, a second optical transform system, aspatial frequency filter and an image sensor, said spatial frequencyfilter being located between said first optical transform system andsaid second optical transform system and said image sensor is locatedafter said second optical transform system, wherein said IR light sourceilluminates said operated area, said first optical transform system isconfigured to transform an IR image of said operated area into afrequency image of said operated area, said spatial frequency filterbeing configured to direct selected frequencies of said frequency imagetoward said second optical transform system, said second opticaltransform system being configured to transform said frequency image backinto said operated area image.
 19. The microsurgery system according toclaim 1, wherein said HMD is a see-through display.
 20. The microsurgerysystem of claim 19, wherein said HMD includes a shutter configured forcontrolling a transparency of at least a portion of said HMD see throughdisplay.
 21. The microsurgery system of claim 20, wherein said shutteris configured to automatically change said transparency according toorientation and/or position changes of said HMD.
 22. The microsurgerysystem of claim 1, wherein said processing device is configured todetermine a virtual Depth of Field (DOF) out of a DOF of said at leastone camera, said processing device being configured to determine whichelements of said operated area image sequences are out of said virtualDOF, and wherein said processing device is configured to blur saidelements of said operated area image sequences that are out of saidvirtual DOF.
 23. The microsurgery system of claim 1, further comprisingan OCT module.
 24. The microsurgery system of claim 1, furthercomprising a light source for illuminating said operated area, whereinsaid light source is configured to transmit light pulses according to aselected time scheme, and wherein said at least one camera issynchronized with said time scheme of said light source.
 25. Themicrosurgery system of claim 1, further comprising an additional HMD,wherein said processing device is further configured to produceadditional magnified image sequences of an additional ROI from saidoperated-area image sequences, and wherein said additional HMD isconfigured to display to an additional user in real time said additionalmagnified image sequences of said additional ROI.
 26. The microsurgerysystem of claim 1, wherein said processing device is further configuredto produce a Three Dimensional (3D) model of said ROI from saidoperated-area image sequences.
 27. The microsurgery system of claim 1,further comprising at least two light sources, each of said at least twolight sources being configured to produce illumination at a respectivespectral band.
 28. The microsurgery system of claim 1, wherein said atleast one camera is configured to operate without an optical zoommechanism.
 29. The microsurgery system of claim 1, further comprising alighting system including a light source and a shutter module, saidshutter module being positioned between said light source and saidoperated area, said light source being configured to produce anillumination beam for illuminating said operated area, said shuttermodule being configured for selectively attenuating spatial portions ofsaid illumination beam.
 30. A method for displaying in real timemagnified digital image sequences of an operated area, the methodcomprising the following procedures: acquiring operated-area imagesequences of said operated area from a viewpoint suspended above saidoperated area; receiving an input indicating a region of interest (ROI)of said operated area, a size of said operated area being larger than asize of said ROI; producing magnified image sequences of said ROI fromsaid operated-area image sequences; and displaying in real-time saidmagnified image sequences of said ROI to a line of sight (LOS) of auser, wherein said magnified image sequences of said ROI are displayedto said user at an angular resolution which is equal to or smaller thanthe angular resolution of a human eye; wherein said LOS of said user isindependent of said viewpoint.